I have tried wixedit and sharp develop and from what I can tell they do not allow you to visually modify the premade templates with a designer. They only allow you to create your own customized dialogs that you can design yourself.
So I am wondering if there is any editors that you can visually modify the design of these templates, especially the mondo template with a point and click editor.
I have also tried SharpSetup and it looks promising how you can design the interface in visual studio, although since I don’t know much about editing wix I am having a hard time comming up with the wix code to make it work.
You can do this with these tools, you just need to download the source from the codeplex website and find the source if the file you want to customise. What you will have to do is change the Id of the file you modify otherwise you’ll get compile errors if you still need to reference dependant items which are in the same dll.